Controlling system for electric motors.



PATENTED MAR. 24, 1908.

H-. 1). JAMES. CONTROLLING SYSTEM FOR ELECTRIC mpToRsf APPLICATION FILED APR. 3,1905.

V R5 *W 3 b E Q III Q "NM 3 7777 I IIII . brake-wheel 17, with which a strap 18 is nor- UNITED STATES HENRY D. JAMES, OF PITTSBI'R-G, PENNSYLVA & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

NIA. ASSIGNOR TO WESTINGHOUSE ELECTRIC CPNTROLLING SYSTEM FOR ELECTRIC vMOTORS.

Specification of Letters Patent.

Patented March 24, 1908.

Application filed April 3, 1905. Serial No. 253,632.

T 0 all whom it may concern.- i Be it known that I, HENRY D. JAMES, a 1 citizen of the United States, and a resident of Pittsburg, in the county of Allegheny and State of Pennsylvania, have invented a new i and useful Improvement in Cont-rolling Systems for Electric Motors, of which the following a specification.

My invention relates to systems of control for electric motors, and particularly to such systems as embody reversing switches and means for automatically efiecti@ acceleration of the motors.

The object of my invention is to provide means for preventing the reversing switch from'being moved from either of its closedcircuit positions to its ofl'" position while the counter electromot'ix e force generated by the motor exceeds a predetermined amount.

A further object of my invention is to provide an improved means for causing sections of the motor regulating resistance to be cut out successively and in a predetermined order as the counter electromotive force of the motor rises.

The single figure of the accompanying drawing illustrates a system of control embodying my invention.

' The system of control com rises, as its constituent elements, a motor 1 aving shunt and series field magnet windings 2 and 3,'re. spectively, a regulating resistance 4, switches 5 for cutting sect-ions ofv the resistance 4 into and out of circuit, operating magnet windin s 6- for the switches 5, interlocking switches 7 t at are operated by the main switches 5, a resistance 8, and a switch 9 for cutting the resistance 8 into and out of circuit, a reversin switch 10, operating magnet windings 1] ans 12 therefor, circuit-breakers 13 and 14, and a master switch 15.

Mounted upon the armature shaft 16, is a mally drawn into engagement by means of a spring 19. The brake may be released by means of an electro-magnet 20, proper circuit connections of the winding of the electro-magnet being made when circuit-breakers 13 and 14 are closed. a When circuit-breaker 13 is open, the ar mature 21 of the motor 1 is connected in a closed circuit with a resistance 22. A comparativel hi h resistance 23 is connected in paralle wit the shunt field magnet windductive electromotive force of the field magnet winding is discharged when its circuit is opened. The series field magnet winding 3 is connected in series with more or less of the regulating resistance 4 and is subdivided, its middle or an intermediate )oint being connected to adjacent termina s 23* of two of the switches 5.

The stationary contact terminals of the switches 5 are connected to points in the regulating resistance 4, the stationary contact terminal 24"of the first switch 25 of the series being also connected to one stationary contact terminal 26 of the circuit-breaker l4.

The outer terminals of the operating magnet windings 6 of the switches 5 are connected to points in the regulating resistance 4 and the inner terminal of each winding is connected to one of the stationary contact terminals of the preceding interlocking switch 7. The other stationary contact terminals of the in terlocking switches are connected to one terminal of resistance 8, and contactfinger 27 of the reversing switch 10 is connected to the other terminal of said resistance.

The first switch 25 of the series is provided with a dashpot 28, which retards closure thereof and causes section 29 of the regulating resistance 4 to remain in circuit during a period of time that may be redeterrnined according to the desired c-on itions of operation.

Operating magnet windin 30 of the switch 9 is connected directly across the supply circuit and is adapted to open the switch 9 when the voltage of the supply circuit exceeds a predetermined amount.

The reversing switch is normally maintained in open-circuit position by means of springs 31 and 32 and is adapted to be retained in its closed-circuit positions by means of retaining magnetwindings 33 and 34, the, terminals of which are connected to contact fingers on the reversing switch 10 in such a manner that they are connected directly between the terminals of the armature winding 21 when the reversing switch occupies one of its closed-circuit positions.

The retaining magnet windings are energized stilliciently' to retain the reversing switch 10 in its corresponding closed-circuit positions when the counter electromotive lflg 2.011 the motor 1, through which the inreversing switch 10 may not return to its 0 en-circuit position and then be moved to t e opposite closed-circuit position while the motor is running at a suificiently high speed in'the opposite direction to generate an e ectromotive force greater than the aforesaid predetermined amount.

The circuit-breakers 13 and 14 are operated by means of eleetro-magnet'windings 35 and 36 and a master switch 15 is provided with a switch arm 37 and suitable contact strips that are so constructed and arranged as to govern the circuits of the operatlng magnet windings l1 and 12 of the reversing switch 10, magnet windings 35 and 36 of the circuit-breakers 13 and 14, and operating magnet windings 6 of the switches 5.

When the master switch arm 37 is moved into engagement with conducting segment 38, a circuit is established from the positive terminal 39 of the system, through operating magnet winding 11 of the reversing switch 10, conducting segment 38 and switch-arm 37, to the negative terminal 40 of the system, thereby energizing the o erati ig -magnet Winding 11, which throws t e reversing switch 10 so that its contact fingers engage the conducting segments onthe brokenlmes F.

f the switch-arm 37 is moved still farther and is brought into engagement with CO1} ducting segment 41, a circuit'isestablished from the positive terminal 39 of the system,

through operating magnet winding 36 of the circuit-breaker 14 and throu operating magnet winding 35 of the circuit-breaker 13,

contact finger 27 of the reversing switch 10, conducting segments 42 and '43. contact 1 finger 44, conducting segment 41, switch-arm sed, rapid closure eing prevented'b the dash 0t 28. The delay in closure 0 the switc 25 permits the motor 1 to start and magnet winding '46 of the main switch 47,

increase in speed and gradually increase the counter electromotive force a circuit is established through operating but sufficient current will not be supplied thereto to operate the switch until the counter electromotiveforce of the motor has risen to a predetermined value that is, until the drop in electromotive force over the section 48 has fallen below a predetermined amount.

When the electromotive force of the motor rises to a sufiicient predetermmed yzilue, the

Whenthe switches 25 and 45 have closed,

switch 47 and the corresponding interlocking switch 49 will close, thereby shunting section 48 0f the resistance and establishing a circuit through operating magnet win 50 of the switch 51, closure of which is not e ected until the current travers' the regulating resistance 4 as fallen below a predetermined amount.

The successive operation of the switches 5 continues, as just described, until all the regulatin resistance 4 has been shunted'or out onto circuit.

- When switch 53 has been closed and section 54 of the regulating resistance cutout of circuit, a circuit is established through 0 erating magnet winding 55, and when t e op in electromotive force over section 56 of the series field magnet winding 3 falls below a predetermined amount,.switch' 57 is closed and cuts out of circuit section 56 of the series field magnet winding3. In like manner, section 58 of the regulating resistance 4 is shunted, by means of switch 59, when the the section 52 of drop of electromotive force over the section 60 falls below a predetermined amount.

It is seen that the sections of the regulating resistance 4 arecut out of circuit successively as the drop. in resistance over the sections falls below a predetermined amount, or

as the counter electromotive force eneratedby the motor increases, and the or er of closure of the switches which shunt the sections of the resistances is overned by the interlocking switches 7. he voltages at which the o eratin ma net windin of the main g g g gs switc es become sufficiently energized to operate their correspondingswitches may be made approximately the same, or unlike, as desire v A One of the inherent difliculties in systems in which the sections of the regulating re sistances are automatically cut out of circuit as the electromotive force of the motor rises, lies in the factthat if the suppl voltage increases, the voltage ap lied to t e'o' crating magnet windings for t e switches whi out thesections of the resistance also rises and the intervals between the closure of the switches shorten. The result is that at just the time when it is desired tov havethe intervals between the closuresof the successive switches prolonged until the s ed of. the

motor may increase, the interva are shortened. The switch 9 is provided for the pur pose of introducing resistance 8 into the circuits of the operat .magnetwindings 6 to retard closure of t eps'witchesiwhen the ch cut electromotive force of the supply circuit rises above a predetermined amount.

I claim as my invention:

1. The combination with a translating device, and a reversing sw tch that normally. occupies an open circuit position, of means for prevent the revers' switch" from being moved 0111 one position ,toanother v1i) 3fThe combination with a translating device and a reversing switch which is normally maintained in its open circuit position, of. means for retaining t e reversing' switch in its closed circuit position while the counmotor, a reversing switch which is normal ating in'agnet windings therefor, of hol operating magnet windings ter electromotive force generated by the translating device exceeds a predetermined amount.

4. The combination with a tran'slating device, a master switch, a reversing switch which is normally maintained in its open circuit position and electro-magiietic oper-' ating means therefor, of electro-magnetic means for retaining the reversing switch in its closed circuit positions while the counter electromotive force generated by the translating device exceeds a predetermined amount.

' 5. The combination with an electric motor, a reversing switch which is normally maintained in its open circuit position and operating magnet windings therefor, of holding magnet windings thatretain the reversing switch in its closed circuit position while the counter electromotive force generated by the motor exceeds a predetermined amount.

6. The combination with an electric motor, a reversing switch which'is normally maintained in open circuit position and oper ating magnet windings therefor, of holding magnet windings the terminals of which are connected to the motor armature terminals and that retain the reversing switch in its closed circuit positions while thecounter electromotive force generated by the motor exceeds a predetermined amount! 7. The combination with anelectric y ering magnet windings the terminals of which are connected to the motor armature terminals by the reversing reversing switch in its closed circuit positions while the electromotive force generated by the motor exceeds a predetermined. amount. 8. T he coi'nhination with a translating de vice, a resistance, and a plurality of switches for cutting out sections of the resistance, of" for said switches maintained in open circuit position and 0 switch and that retain the each having a terminal connected to points in the resistance, interlocking switches operated by the aforesaid switches which control the circuits of the 'operating magnet windings, a resistancein series with the operating magnet windings ,and means for cutting said resistance into thecircuit ofthe operating magnet windings when the voltage applied to the translating device exceeds a predetermined value. i

9. The combination with a translating device, a resistance, and a plurality of switches for cutting out sections of the resistance, of operating magnet windings for said switches each having a terminal connected to points in the resistance, interlocking switches operated by the aforesaid switches which control the circuits of the operating magnet windings, a resistance in series with the operating magnet windings, and a switch for cutting said resistance intothe circuit of the operating magnet windings when the voltage applied to the translating device exceeds a predetermined value.

'10. The combination with ii -translating and a plurality ofswitches for cutting out sections of there device, a resistance,

sistahce, of operating magnet windings for said switches each having a terminal connected to )oints in the resistance, interlock ing switces operated by the aforesaid switches which control the circuits. of the operating magnet windings, a resistance in series with the operating magnet windings, a switch, and means for causin the said switch to operate to cut the sai resistance into the circuit of the'operating magnet windings when the voltage applied to the translating device exceeds a predetermined value.

11.. The combination with an electric motor having a series field magnet winding, a

resistance in circuit therewith, and switches for removing the resistance and a portion of the series field magnet winding from circuit, of o crating magnet windings for the switc es, terminals of which are connected to the resistance and series field magnet winding at intervals, interlocking switches 0 er.- ated by the aforesaid switches for control ing the circuits of the operating magnet wind.- ings, a second resistance, and means for inserting the same in circuit with the magnet windings when the voltageapplied to the de vice exceeds a predetermined value.

In testimony whereof, I have hereunto subscribed .my name this 22nd day of March,

I IENR Y D. JABIES.

Witnesses O'r'io S. SIGHAIRER, BIRNEY limes. 

